@JesusFreak
Hey Bryant
It is always tricky getting the identity of an elm. But more or less they are all treated the same for bonsai. The techniques are the same across the genus, so if it takes you a couple years to nail down for certain which species or hybrid elm you have that is not really a problem.
The botanically significant traits are flower color, and the phenology of WHEN they flower, some flower spring, some species late winter, some flower in autumn. Of course only an older tree would flower so this is not something you will see any time soon, though mature bonsai elms will flower even in a bonsai pot. Next trait, and this can be used during winter, is the arrangement of scales on the winter buds. The protective scales, or sheath leaves that cover the winter buds, the pattern is diagnostic for species. The arrangement of the scars of the vascular bundles in the abscission scar where the leaves were is another diagnostic trait used to separate one elm from another. For example, the vascular bundles can be in a 'U' shape or 'V' shape or other patterns. Leaf shape & size and number of veins is also diagnostic. Often to be certain, you check each trait as the year goes by, and by the end of a year or two you will have the checklist. THen you sit down with a botanical dichotomous key, and check the questions off, jump to the next until you have your identity. Pain in the ass.
Or you can sit and read Wikipedia and go through each entry. Some have great detail as to what identifies the species, some of Wikipedias entries are pretty vague. All in all I've found most of Wikipedia's information accurate, even though sometimes it is woefully vague sometimes. It rare that I say, "that's plain wrong". Most of the time Wikipedia is correct to really good.
en.wikipedia.org
Also read the general article on elms.
en.wikipedia.org